AVERAGING METHOD FOR ELIMINATION OF PERIODIC STRAYS AND A CIRCUIT ARRANGEMENT FOR APPLYING THE METHOD

摘要

An averaging method for elimination of periodic strays, especially of the strays originated in an environment (9) comprising a mains supply network, in which method an averaging computer (6) processes a set of signals picked up from an examined subject (8) e.g. a human scalp by means of electrodes (10) which set is fed forward through an instrumentation amplifier (7) to the averaging computer (6). A timing circuit in the set-up for measuring evoked responses comprises: a quartz oscillator circuit (1) of frequency fgz, a divider circuit (2) and a triggering circuit (3) introducing desynchronization of frequency 1/T of the external stimuli from transducers (4) driven by a stimulator (5) and of sweeps of the averaging procedure run in the averaging computer (6) having regard to the frequency 1/t of periodic strays.